The present invention relates to battery modules, and specifically relates to a battery module containing a cooling agent.
In recent years, secondary batteries which can be used repeatedly have been used as power sources for driving mobile electronic devices, portable communication devices, etc., to save resources and conserve energy. Further, to reduce the amount of use of fossil fuel and reduce the amount of emission of carbon dioxide, the secondary batteries have been expected to be used as a power source for driving a vehicle.
Specifically, the technique in which general-purpose batteries are connected together in parallel or in series to form a battery module and in which the battery modules are combined together to be used for various purposes has been adopted. This technique enables downsize and light weight of the battery module by increasing performance of the batteries (cells) which form the battery module. Thus, workability can be improved in combining the battery modules, and flexibility in mounting the battery module in areas of limited space, such as a vehicle, can be increased.
When cells are arranged in intimate proximity to each other, the energy density of a battery module can be increased, and the size of the battery module can be reduced. However, if an internal short-circuit or the like is formed in any one of the cells, and heat is abnormally generated in the cell (hereinafter simply referred to as “in case of abnormal heat generation”), a normal cell located in the periphery of the cell in which heat is abnormally generated (abnormal cell) is subjected to high-temperature heat, so that the abnormally generated heat may spread in a chain reaction. In view of the foregoing, U.S. Pat. No. 7,433,794 B1 proposes a cooling tube capable of releasing a cooling agent in case of abnormal heat generation. The cooling tube is configured such that part of the cooling tube melts in case of abnormal heat generation, and the cooling agent is released when the cooling tube melts. Moreover, Japanese Patent Publication No. 2007-200880 proposes a battery pack in which a fire extinguishing safety apparatus is provided, wherein in case of abnormal heat generation, an extinguishant is sprayed from the fire extinguishing safety apparatus.